A lithium-ion secondary battery has a higher energy density and is operable at a high voltage compared to conventional secondary batteries. Therefore, it is used for information devices such as a cellular phone, as a secondary battery which can be easily reduced in size and weight, and nowadays there is also an increasing demand for the lithium-ion secondary battery to be used as a power source for electric vehicles and hybrid vehicles.
The lithium-ion secondary battery includes a cathode layer, an anode layer, and an electrolyte layer arranged between them. An electrolyte to be used in the electrolyte layer is, for example, a non-aqueous liquid or a solid. When the liquid is used as the electrolyte (hereinafter, the liquid being referred to as “electrolytic solution”), it easily permeates into the cathode layer and the anode layer. Therefore, an interface can be easily formed between the electrolytic solution and active materials contained in the cathode layer and the anode layer, and the battery performance can be easily improved. However, since commonly used electrolytic solutions are flammable, it is necessary to have a system to ensure safety. On the other hand, if a nonflammable solid electrolyte (hereinafter referred to as “solid electrolyte”) is used, the above system can be simplified. As such, a lithium-ion secondary battery provided with a layer containing a solid electrolyte has been suggested (hereinafter, the layer being referred to as “solid electrolyte layer” and the battery being referred to as “all-solid-state battery”).
As a technique related to such a lithium-ion secondary battery, for example Patent Literature 1 describes quickly charging a lithium-ion secondary battery prepared with a polymer electrolyte, by means of a heating element set as having a temperature of 60° C. adhered to an outer surface of the battery. Patent Literature 2 describes heating a secondary battery prepared with a polymer electrolyte to 50° C. to charge the battery. Also, Patent Literature 3 describes heating a battery for driving an electric vehicle to 30° C. thereafter charging the battery.